The owners of two Colorado drone companies that flew their unmanned aerial vehicles over flooded areas and collected data were warned this week they face arrest and fines if they violate airspace rules.

“I told them to cease-and-desist by order of the sheriff and the incident commander,” said Allen Bishop, a Boulder County sheriff’s reserve volunteer, amateur radio operator and a nationally recognized expert on drones.

He said the concern is a helicopter engine could “ingest” one of the drones, causing it to crash with rescued flood victims on board.

Bishop said he contacted a drone company in Boulder and Falcon UAV in Aurora, owned by Chris Miser. The Boulder company could not be reached for comment.

Miser, who was first told on Saturday he couldn’t fly, wrote a blog post about the incident that has been widely quoted.

“Grounded by FEMA” the headline read.

He said that on Thursday “while all National Guard aircraft were grounded due to weather Falcon UAV was proud to have been the only aircraft that was able to take flight to support the flood efforts in Lyons.”

Mike Chard, the director of Boulder’s emergency management office, said it was unfair to pin the decision on FEMA when it was an incident commander who made the decision.

But Miser on Tuesday stuck by his piece.

He said he went to the flooded area “unsolicited.”

“I said, ‘Hey, I’ve got a couple of UAVs (unmanned aerial vehicles). How can I help?’ They were open to the opportunity so they let me go fly,” Miser said.

He said he provided data from the drone, which showed close-ups of damage, to emergency officials.